This invention relates to earth-working equipment and, more particularly, to more efficient use of resonance as an aid to the operation of bulldozers and the like.
Bulldozers and like earth-working equipment such as graders and scrapers are in common use on construction sites and elsewhere. Conventionally, a steady force, i.e., the tractive force of the vehicle, furnishes the power necessary to perform the bulldozing function. A good deal of effort has been devoted to the use of vibration to facilitate earth-working operations.
Prior efforts to use vibration to aid bulldozing have for the most part taken the approach of vibrating the mold board, as typically shown in Cobb et al U.S. Pat. No. 3,770,322 and Bodine U.S. Pat. No. 3,367,716. An exception is Cunningham U.S. Pat. No. 3,478,450, in which a separate cutter blade under the bottom edge of the mold board is vibrated. The cutter blade is supported for reciprocal motion by arms pivotably attached to the mold board. A source of vibrations attached to the cutter blade assembly applies an unbalanced force to the cutter blade to set up a forced vibration of the cutter blade in forward and aft directions.
A principal problem in conventional dozers and like machines using vibration is the transmission of vibration energy to the machine itself rather than the cutter blade. Vibration is conventionally applied to the cutting blade by an eccentric oscillator in all directions about the axis of the oscillator. Only the component of such forces in the direction of the operation of the cutting blade, i.e., forwardly, are useful. All other components of force act on the machine itself and set up unwanted vibrations in the machine. Because of limitations on the size of vibration loads which can be applied to the machine, the output forces of the oscillator must be kept relatively low, greatly inhibiting the utility of the vibration system for its intended function.